當(dāng)你食用含糖多的食物時, 你的味蕾、腸道和大腦都會敏銳地注意到它。這種對大腦犒賞系統(tǒng)的激活與身體對酒精或者尼古丁的上癮并沒有什么兩樣——糖的過多攝入會使多巴胺分泌量激增，并且會使你渴求更多。Nicole Avena解釋了為什么人們應(yīng)當(dāng)有節(jié)制地享用糖果與甜食。
Picture warm, gooey cookies, crunchy candies, velvety cakes, waffle cones piled high with ice cream.
想象一下溫?zé)?、綿軟的曲奇餅干，酥脆的糖果，天鵝絨般柔軟的蛋糕，還有堆著高高冰淇淋的華夫蛋筒。
Is your mouth watering?
你已經(jīng)流口水了么？
Are you craving dessert?
你想要吃甜點了么？
Why?
為什么？
What happens in the brain that makes sugary foods so hard to resist?
你的大腦中到底發(fā)生了什么才使得含糖類食物變得如此不可抗拒？
Sugar is a general term used to describe a class of molecules called carbohydrates, and it's found in a wide variety of food and drink.
糖是一個用來描述一類被稱為碳水化合物的分子的統(tǒng)稱術(shù)語，在很多食品與飲料中都可以找到它。
Just check the labels on sweet products you buy.
只要去看一下你買的甜食上的標(biāo)簽。
Glucose, fructose, sucrose, maltose, lactose, dextrose, and starch are all forms of sugar.
葡萄糖、果糖、蔗糖、麥芽糖、乳糖、右旋糖，還有淀粉都是糖的各類形式。
So are high-fructose corn syrup, fruit juice, raw sugar, and honey.
果糖含量很高的玉米糖漿、果汁、粗糖，還有蜂蜜也是一樣的。
And sugar isn't just in candies and desserts, it's also added to tomato sauce, yogurt, dried fruit, flavored waters, or granola bars.
而且，糖不僅存在于糖果和甜點中，它也被添加于番茄醬、酸奶、果脯、加味水，亦或是燕麥棒中。
Since sugar is everywhere, it's important to understand how it affects the brain.
正因為糖無處不在，所以要明白它如何影響大腦才顯得很重要。
What happens when sugar hits your tongue?
當(dāng)糖分接觸到你的舌頭時會發(fā)生什么？
And does eating a little bit of sugar make you crave more?
只吃一點點糖會使你渴求更多么？
You take a bite of cereal.
你咬了一口麥片。
The sugars it contains activate the sweet-taste receptors, part of the taste buds on the tongue.
它所含的糖分會觸發(fā)甜味受體，也就是舌頭上味蕾的一部分。
These receptors send a signal up to the brain stem,
這些受體會向腦干發(fā)送信號，
and from there, it forks off into many areas of the forebrain, one of which is the cerebral cortex.
從那里，它會分支進(jìn)入前腦的許多部位，其中一個就是大腦皮層。
Different sections of the cerebral cortex process different tastes: bitter, salty, umami, and, in our case, sweet.
大腦皮層的不同部分會處理不同的味覺：苦、咸、鮮，以及我們現(xiàn)在所談的甜。
From here, the signal activates the brain's reward system.
從這里（大腦皮層），信號會激活大腦的犒賞系統(tǒng)。
This reward system is a series of electrical and chemical pathways across several different regions of the brain.
犒賞系統(tǒng)是一系列穿過大腦不同部位的電化學(xué)途徑。
It's a complicated network, but it helps answer a single, subconscious question: should I do that again?
它是個復(fù)雜的網(wǎng)絡(luò)，但是它會幫助解答一個單一的、潛意識中存在的問題：“我應(yīng)該再來一次嗎？
That warm, fuzzy feeling you get when you taste Grandma's chocolate cake?
享受當(dāng)你品嘗祖母做的巧克力蛋糕時那種溫暖、卻有些模糊了的感覺？
That's your reward system saying, "Mmm, yes!"
然后你的犒賞系統(tǒng)就會說："嗯，當(dāng)然了！”
And it's not just activated by food.
然而，它不僅會被食物激活。
Socializing, sexual behavior, and drugs are just a few examples of things and experiences that also activate the reward system.
社交、性行為，還有毒品都只是可激活犒賞系統(tǒng)的事物的幾個例子而已。
But overactivating this reward system kickstarts a series of unfortunate events: loss of control, craving, and increased tolerance to sugar.
但是過渡激活犒賞系統(tǒng)會導(dǎo)致一系列不幸的事：失控、渴求，還有對糖分耐受度的提升。
Let's get back to our bite of cereal.
讓我們回到吃麥片的例子上去。
It travels down into your stomach and eventually into your gut.
它會來到你的胃里并最終到達(dá)腸道。
And guess what?
然后你猜怎么著？
There are sugar receptors here, too.
那里也存在著糖分受體。
They are not taste buds,
它們不是味蕾，
but they do send signals telling your brain that you're full or that your body should produce more insulin to deal with the extra sugar you're eating.
但它們也會發(fā)送信號來向你的大腦表明你已經(jīng)吃飽了，或者你的身體需要生產(chǎn)更多的胰島素來幫助消化你額外攝入的糖分。
The major currency of our reward system is dopamine, an important chemical or neurotransmitter.
犒賞系統(tǒng)的“主要流通貨幣”是多巴胺，一種重要的化學(xué)物質(zhì)或者說是神經(jīng)遞質(zhì)。
There are many dopamine receptors in the forebrain, but they're not evenly distributed.
前腦中存在著許多多巴胺受體，但是它們的分布并不均勻。
Certain areas contain dense clusters of receptors, and these dopamine hot spots are a part of our reward system.
某些部位的受體密集成群，并且，這些多巴胺熱點就是我們犒賞系統(tǒng)的一部分。
Drugs like alcohol, nicotine, or heroin send dopamine into overdrive, leading some people to constantly seek that high,
像酒精、尼古丁或者是海洛因一類的麻醉藥品會使得多巴胺分泌超過限度，以至于令有些人不停地尋求那種快感，
in other words, to be addicted.
換一句話說，就是上癮了。
Sugar also causes dopamine to be released, though not as violently as drugs.
糖分也會促進(jìn)多巴胺分泌，盡管不像毒品那樣極端。
And sugar is rare among dopamine-inducing foods.
而且，糖分在誘發(fā)多巴胺的食物中也非常少見。
Broccoli, for example, has no effect, which probably explains why it's so hard to get kids to eat their veggies.
比如說，西蘭花就對此沒有什么影響，也許這就能解釋為什么讓孩子們多吃蔬菜是如此的難。
Speaking of healthy foods, let's say you're hungry and decide to eat a balanced meal.
談到健康食品，比方說你感覺很餓決定要享用營養(yǎng)均衡的一餐。
You do, and dopamine levels spike in the reward system hot spots.
用過餐后，犒賞系統(tǒng)熱點中的多巴胺含量就會激增。
But if you eat that same dish many days in a row, dopamine levels will spike less and less, eventually leveling out.
但如果你連續(xù)很多天都吃這同一餐，多巴胺的增量就會越來越少，最終達(dá)到穩(wěn)定。
That's because when it comes to food, the brain evolved to pay special attention to new or different tastes.
這是因為在食物問題上，大腦演變得對那些全新的亦或是不同的味覺異常敏感。
Why?
這是為什么呢？
Two reasons: first, to detect food that's gone bad.
有兩個原因：第一，為了檢查出已經(jīng)變質(zhì)的食物。
And second, because the more variety we have in our diet, the more likely we are to get all the nutrients we need.
第二，我們的飲食越多樣，我們就越有可能得到所有我們需要的營養(yǎng)。
To keep that variety up, we need to be able to recognize a new food, and more importantly, we need to want to keep eating new foods.
為了保持那種飲食多樣性，我們需要能夠識別新的食物，更重要的是，我們需要維持想吃新食物的欲望。
And that's why the dopamine levels off when a food becomes boring.
這就是為什么當(dāng)食物一成不變的時候多巴胺的分泌就會逐漸趨于平穩(wěn)。
Now, back to that meal.
現(xiàn)在，讓我們回到那一餐的問題上。
What happens if in place of the healthy, balanced dish, you eat sugar-rich food instead?
如果用富含糖分的食物取代健康、平衡的飲食會發(fā)生什么呢？
If you rarely eat sugar or don't eat much at a time, the effect is similar to that of the balanced meal.
如果你不怎么攝入糖分或者不一次攝入太多，它帶來的影響就和平衡的飲食沒有什么兩樣。
But if you eat too much, the dopamine response does not level out.
但是如果你吃的太多，多巴胺的分泌就會不穩(wěn)定。
In other words, eating lots of sugar will continue to feel rewarding.
換句話說，攝取大量糖分會持續(xù)使犒賞系統(tǒng)興奮。
In this way, sugar behaves a little bit like a drug.
從這個角度來講，糖類就有一點像毒品了。
It's one reason people seem to be hooked on sugary foods.
這就是一個人們之所以對含糖食品著迷的原因。
So, think back to all those different kinds of sugar.
這樣，想想之前那些所有不同種類的糖。
Each one is unique, but every time any sugar is consumed,
每一種都是獨特的，但是每一次攝取這些糖分的時候，
it kickstarts a domino effect in the brain that sparks a rewarding feeling.
它就會在大腦中引發(fā)多米諾骨牌一般的效應(yīng)，并激活犒賞系統(tǒng)。
Too much, too often, and things can go into overdrive.
太多，太頻繁，就可能會過度。
So, yes, overconsumption of sugar can have addictive effects on the brain,
因此，沒錯，糖分的過度攝取可以使大腦上癮，
but a wedge of cake once in a while won't hurt you.
不過，偶爾品嘗一塊蛋糕并不會有什么壞處。
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